Tubular bagging machines are known from the state of the art, for example from German Patent 35 38 723, in which the movement of the cross-welding jaws is controlled by means of cam plates. A cam-plate pair is thereby in particular provided, which is operatively connected directly with the pair of cross-welding jaws and is constructed such, that upon a complete rotation of the cam plate one operating cycle of the respective cross-welding jaw is carried out. Since the shape of each respective cam plate is fixed, it is not possible to adapt the movement of the cross-welding jaw to the respective operating conditions. It is in particular not possible to control the necessary sealing or welding times depending on the type of the material of the tubular bag or of the foil, the temperature of this material or the temperature of the welding jaws. It is furthermore not possible to adjust the respectively needed contact pressure of the cross-welding jaws to the requirements. All of this has the result under unfavorable operating conditions that either no sufficient welding or sealing occurs or that the material is heated up too much by the cross-welding jaws, and that holes or defects can be created.
A further disadvantage of the known cam-plate control of the cross-welding jaws is, that the cross-welding jaws often hit one another hard due to the acceleration caused by the cam plates, so that high material stress occurs. This has the result, that the cross-welding jaws must be manufactured of stronger materials and must be dimensioned accordingly. All of this increases the manufacturing expenses of the welding jaws and has the result, that greater masses must be moved.
A further disadvantage of the known design of a tubular bagging machine is, that an adjustment of the movement of the cross-welding jaws to the possible cycle time resulting from the material of the tubular bag is hardly possible. An increase in the peripheral speed or rather the rotational speed of the cam plates does result in a shortening or extending of the operating cycle, however, with the result, that at a suitable adjustment of the sealing or welding time, the times for the remaining operating steps are also extended or shortened, so that, for example, a satisfactory filling of the bag is not possible or is possible only at a considerable expense.
The basic purpose of the invention is to produce a method and an apparatus of the above-mentioned type, which with a simple design and operatively safe handling enable a simple adjustment to the respective operating conditions and avoid the disadvantages of the state of the art.